In a smart system, an onboard system transmits a request signal. A portable device receives the request signal. An LF demodulation portion demodulates the request signal to acquire request data and returns an answer signal based on acquisition of the request data. The onboard system receives the answer signal and performs smart drive based on reception of the answer signal. The onboard system also transmits a specified counter-RA signal. A switching circuit of the portable device outputs the received counter-RA signal to a modulation portion while bypassing the LF demodulation portion. The modulation portion performs RF modulation using the counter-RA signal to acquire a counter-RA modulation signal and transmits the counter-RA modulation signal. When receiving the counter-RA modulation signal, the onboard system determines whether to allow or disallow the smart drive based on delay time of timing to receive the counter-RA modulation signal with reference to timing to transmit the counter-RA signal. This enables to suppress variations in the transmission/reception delay time inherent in the smart system.